<p>This study investigated the effect of metallographic preparation through mechanical, chemical, and electrolytic polishing on phase identification and residual stress analysis in 304L stainless steel, which exhibits the transformation-induced plasticity (TRIP) effect. The surface martensite content and residual stresses were measured in the as-received condition, with hot rolling and after strain-induced martensitic transformation by cryogenic rolling. The results showed that surface martensite associated with thermomechanical (hot rolling) processing decreased progressively with mechanical, chemical, and electrolytic polishing. Corresponding differences emerged in the magnitude of surface compressive residual stresses. Variations in martensite content were also observed among the cryogenically rolled samples, depending on the polishing method. This way, metallographic preparation significantly affected the phase quantification results obtained through X-ray diffraction (XRD), magnetic ferritescopy, and the residual stress values measured by XRD. The surface preparation technique also strongly influenced the quality of electron backscatter diffraction (EBSD) pattern acquisition. In contrast, acoustic birefringence stress measurements showed no significant dependence on the metallographic preparation method.</p>